Polishing system with three headed carousel

ABSTRACT

Embodiments of the present invention provide a polishing module configured to use in a polishing system. The polishing module comprises a base member, two polishing stations disposed on the base member, one load cup, and a carousel having three polishing heads.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the invention generally relate to an apparatus and methodfor polishing or planarization of semiconductor substrates.

2. Description of the Related Art

Sub-micron multi-level metallization is one of the key technologies forthe next generation of ultra large-scale integration (ULSI). Themultilevel interconnects that lie at the heart of this technologyrequire planarization of interconnect features formed in high aspectratio apertures, including contacts, vias, trenches and other features.Reliable formation of these interconnect features is very important tothe success of ULSI and to the continued effort to increase circuitdensity and quality on individual substrates and die.

In the fabrication of integrated circuits and other electronic devices,multiple layers of conductive, semi-conductive, and dielectric materialsare deposited on or removed from a surface of a substrate. Thin layersof conductive, semiconductive, and dielectric materials may be depositedby a number of deposition techniques. As layers of materials aresequentially deposited and removed, the uppermost surface of thesubstrate may become non-planar across its surface and requireplanarization.

Planarization is generally performed using Chemical Mechanical Polishing(CMP) and/or Electro-Chemical Mechanical Deposition (ECMP). Aplanarization method typically requires that the substrate be mounted ina wafer head, with the surface of the substrate to be polished exposed.The substrate supported by the head is then placed against a rotatingpolishing pad. The head holding the substrate may also rotate, toprovide additional motion between the substrate and the polishing padsurface. Further, a polishing slurry (typically including an abrasiveand at least one chemically reactive agent therein, which are selectedto enhance the polishing of the topmost film layer of the substrate) issupplied to the pad to provide an abrasive chemical solution at theinterface between the pad and the substrate. The combination ofpolishing pad characteristics, the specific slurry mixture, and otherpolishing parameters can provide specific polishing characteristics.

Polishing is generally performed in multiple steps, each having specificpolishing characteristics, to achieve desired results. A polishingsystem generally has two or more polishing pads configured to performdifferent polishing steps, and a substrate transfer assembly configuredto transfer the substrates among the two or more polishing pads.

However, it remains challenging to achieve high throughput andflexibility to meet process requirements in a polishing system.

Therefore, there is a need for a polishing system with flexibility andimproved throughput.

SUMMARY OF THE INVENTION

The present invention provides methods and apparatus for polishingsemiconductor substrates with improved throughput.

One embodiment of the present invention provides a polishing moduleconfigured to use in a polishing system comprising a base member, twopolishing stations disposed on the base member, wherein each of the twopolishing stations is configured to polish substrates, a carouselsupported by the base member, wherein the carousel comprises threesubstrate heads each configured to transfer a substrate and polish thesubstrate against the two polishing stations, and the carousel isconfigured to simultaneously rotate the three substrate heads about acarousel axis, and a load cup disposed on the base member, wherein theload cup is configured to load substrates to the three substrates headsand to unload substrates from the three polishing heads, and the twopolishing stations and the load cup are positioned to allow simultaneousalignment of each of the three substrate heads with one of the twopolishing stations and the load cup.

Another embodiment of the present invention provides a polishing systemcomprising a factory interface configured to receive unpolishedsubstrates from substrate transferring cassettes and transfer polishedsubstrates to the substrate transferring cassettes, a substratetransferring platform configured to receive substrates from the factoryinterface, a polishing assembly configured to polishing substrates inone or more polishing steps, wherein the polishing assembly comprises afirst polishing module comprises a first base member, first and secondpolishing stations disposed on the first base member, a first carouselsupported by the first base member, wherein the first carousel comprisesthree substrate heads each configured to transfer a substrate and polishthe substrate against the first and second polishing stations, and thefirst carousel is configured to simultaneously rotate the threesubstrate heads about a first carousel axis, and a first load cupdisposed on the first base member, wherein the first polishing station,the second polishing station and the first load cup are positioned toallow simultaneous alignment of each of the three substrate heads of thefirst carousel with one of the first polishing station, the secondpolishing station and the first load cup, a polishing robot configuredto transfer substrates from the substrate transferring platform to thepolishing assembly, and a cleaning assembly to clean polished thesubstrates.

Yet another embodiment of the present invention provides a method forpolishing a substrate comprising transferring a first substrate using asubstrate transferring belt towards a polishing assembly, transferringthe first substrate from the substrate transferring belt to a first loadcup of the polishing assembly, loading the first substrate from thefirst load cup to a first substrate head mounted on a first carouselhaving three polishing heads, aligning the first substrate head with afirst polishing station of the polishing assembly, polishing the firstsubstrate in the first polishing station, aligning the first substratehead with the first load cup, and unloading the first substrate from thefirst substrate head to the first load cup.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention can be understood in detail, a more particular description ofthe invention, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1 is a schematic top view of a polishing module in accordance withone embodiment of the present invention.

FIG. 2 is a schematic sectional side view of the polishing module ofFIG. 1.

FIG. 3 is a schematic plan view of a polishing system in accordance withone embodiment of the present invention.

FIG. 4 is a schematic plan view of a polishing system in accordance withanother embodiment of the present invention.

It is to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements disclosed in oneembodiment may be beneficially utilized on other embodiments withoutspecific recitation.

DETAILED DESCRIPTION

The present invention provides methods and apparatus for polishingsemiconductor substrates with improved throughput and improvedflexibility. In one embodiment of the present invention, three polishingheads are mounted on a carousel and are configured to transfer andprocess substrates among two polishing stations and one load cup. In oneembodiment, two three headed carousels are used together. In anotherembodiment, a three headed carousel is used in combination withpolishing heads mounted on pivoting arms.

FIG. 1 is a schematic top view of a polishing module 100 in accordancewith one embodiment of the present invention. FIG. 2 is a schematicsectional side view of the polishing module 100 of FIG. 1.

The polishing module 100 is configured to be used alone or incombination in a polishing system. The polishing module 100 generallycomprises a base member 101. Two polishing stations 102 a, 102 b, and aload cup 103 are disposed on the base member 101. The polishing module100 further comprises a carousel 110 mounted on the base member 101. Thecarousel 110 comprises three head systems 107 a, 107 b, 107 c, each ofwhich is configured to receive, transfer and process a substrate. Thecarousel 110 is configured to rotate the head systems 107 a, 107 b, 107c simultaneously and to align the head systems 107 a, 107 b, 107 c withthe polishing stations 102 a, 102 b, and the load cup 103.

Each polishing stations 102 a, 102 b comprises a rotatable platen 121 onwhich a polishing pad 124 is placed. Each polishing station 102 a or 102b further includes a conditioner head 123 adapted on a rotatable arm122. A detailed description for the rotatable platen 121 and thepolishing pad 124 may be found in co-pending U.S. patent applicationSer. No. 10/880,752, filed on Jun. 30, 2004, entitled “Method andApparatus for Electrochemical Mechanical Processing”, which is hereinincorporated as reference. A detailed description for the polishing pad124 may be found in co-pending U.S. Pat. No. 6,575,825, entitled “CMPPolishing Pad”, which is herein incorporated as reference. Each of thepolishing stations 102 may be configured to conduct chemical mechanicalpolishing (CMP), electrochemical mechanical polishing (ECMP) or buffing.

Each of the head systems 107 a, 107 b, 107 c is configured to receiveone substrate, transfer the substrate among the polishing stations 102a, 102 b and the load cup 103, and polish the substrate by pressing thesubstrate against any one of the polishing pads 124 on the polishingstations 102 a, 102 b. In one embodiment, the carousel 110 is supportedby a center post 118 on the base 101. The carousel 110 is rotatable onthe center post 118 about a carousel axis 104 by a motor assembly (notshown) located within the base 101. In one embodiment, the motorassembly may comprise a servo motor.

In one embodiment, the three head systems 107 a, 107 b, 107 c areidentical and mounted on a carousel base plate 119 at equal angularintervals about the carousel axis 104. The center post 118 supports thecarousel base plate 119 and allows the motor assembly to rotate thecarousel base plate 119.

Each head system 107 a, 107 b, 107 c comprises a substrate head 112which is rotatable about its own axis by a head-rotation motor 111connected to the substrate head 112 by a shaft. The substrate heads 112can rotate independently driven by the respective head-rotation motor111. Each head system 107 a, 107 b, 107 c is independently movable alonga slot 116 formed radially on the carousel base plate 119. In oneembodiment, for each head system 107 a, 107 b, 107 c, the linearmovement along the respectively slot 116 is realized through a slidemounted around the shaft between the head-rotation motor 111 and thesubstrate head 112. The linear movement of each head system 107 a, 107b, 107 c is configured to adjust the radial position of each head system107 a, 107 b, 107 c during alignment with the polishing stations 102 a,102 b, and the load cup 103. The liner movement may also providesweeping motion during polishing.

During processing, two of the three head systems 107 a, 107 b, 107 c arepositioned above a respective polishing station 102 a, 102 b. Thesubstrate retained on each substrate head 112 is lowered using substratelowering/raising mechanism within the head system 107 a, 107 b, or 107c. Polishing is conducted via a relative motion produced between thesubstrate retained therein and the platen 121 of the respectivepolishing station 102 a, 102 b. In one embodiment, the relative motionmay be a result of a rotation of the platen 121, a rotation of thesubstrate head 112 and a sweeping motion of the substrate head 112. Asuitable head system may be a Titan® polishing head available fromApplied Materials, Inc. located in Santa Clara, Calif. A detaileddescription of the substrate head 112 may be found in U.S. Pat. No.6,183,354, entitled “Carrier Head with a Flexible Membrane for aChemical Mechanical Polishing”, and co-pending U.S. patent applicationSer. No. 11/054,128 filed on Feb. 8, 2004, entitled “Multi-chamberCarrier Head with a Flexible Membrane”, which are herein incorporated asreference.

The load cup 103 is positioned on the base member 101 such that when twoof the three head systems 107 a, 107 b, 107 c are in polishing positionabove the respective polishing stations 102 a, 102 b, the third headsystem may be aligned to the load cup 103. The load cup 103 isconfigured to receive/pass a substrate from/to a substrate transferor,such as a robot, pass/receive the substrate to/from each of the headsystems 107 a, 107 b, 107 c. In one embodiment, the load cups 103 may bealso adapted to be a wash station for a substrate to be cleaned therein.A detailed description of a load cup may be found in co-pending U.S.patent application Ser. No. 10/988,647, filed on Nov. 15, 2004, entitled“Load Cup for Chemical Mechanical Polishing”, which is hereinincorporated as reference.

For a polishing system which is capable of performing multiple-steppolishing using multiple polishing stations, flexibility and highthroughput are both desired but are usually conflicting. On the onehand, ideal flexibility may be achieved by allowing “random access” ofeach polishing station. The random access may be achieved by usingrobots to transfer substrates among polishing stations. However, thisrandom access resolution has a high overhead time of loading/unloadingbecause substrates have to be loaded/unloaded at each polishing station,thus, reducing throughput. On the other hand, a carousel structure,which uses a carousel to transfer polishing heads and substrates mountedthereon among the multiple polishing stations, enables high throughputsince loading/unloading is required only once for the entire processing.However, the carousel structure dictates a fixed number of sequentialsteps with limited flexibility.

The polishing module 100, which has a three-headed carousel and twopolishing stations, combines flexibility to a high throughput carouseldesign by reducing the number of polishing heads of the carousel andallow two or more carousels to be used in combination. Duringprocessing, two of the three polishing heads are located over the twopolishing stations performing polishing, while the third polishing headis positioned over the load cup performing loading and unloadingsimultaneously. The arrangement minimizes loading/unloading overheadbecause loading/unloading is performed in parallel with the polishingprocess. Two or more polishing modules may be used in combination foradded flexibility.

FIG. 3 is a schematic plan view of a polishing system 200 in accordancewith one embodiment of the present invention. The polishing system 200generally includes a factory interface 201, a substrate transferringmechanism 202, a polishing robot 203, a polishing assembly 204, and acleaning assembly 205.

The factory interface 201 generally comprises an internal robot 211which is configured to transfer substrates to be polished from one ormore substrate storage cassettes 212 to the substrate transferringmechanism 202, and to transfer polished and cleaned substrates from thecleaning assembly 205 back to the one or more substrate storagecassettes 212.

The internal robot 211 only contacts substrates when the substrates arefree of polishing solution and is sometimes referred to as a dry robot.In the embodiment, four substrate storage cassettes 212 are connected tothe factory interface. In one embodiment, the internal robot 211 may bemounted on a rail or track 213 configured to position the internal robot211 laterally within the factory interface 201, thereby increasing therange of motion of the internal robot 201.

In one embodiment, the factory interface 201 may have an outlet port 214designated to deliver unpolished substrates to the substratetransferring mechanism 202. The factory interface 201 may have an inletport 215 designated to receive polished substrates from the cleaningassembly 205.

In one embodiment, the internal robot 211 of the factory interface 201may be queued to transfer substrates to the substrate transferringmechanism 202 in synchronization with substrate transfer from thesubstrate transferring mechanism 202 to the polishing assembly 204 bythe polishing robot 203.

In one embodiment, the substrate transferring mechanism 202 comprises atransferring belt 221 disposed between the factory interface 201 and alocation within a range of motion of the polishing robot 203. Duringprocessing, the transferring-belt 221 may move a substrate transferringsurface from the factory interface 201 towards the polishing robot 203to carry a plurality of substrates 206 from the factory interface 201towards the polishing assembly 204.

The polishing assembly 204 is modular and configured to performdifferent polishing recipes. In one embodiment, the polishing assembly204 comprises two polishing modules 231, 241 disposed side by side. Inone embodiment, the polishing modules 231, 241 may be similar to thepolishing module 100 of FIG. 1.

The polishing module 231 comprises two polishing stations 233 a, 233 b,one load cup 234, and a carousel 232 configured to align three polishingheads 235 a, 235 b, 235 c with the polishing stations 233 a, 233 b, andthe load cup 234. The polishing module 241 comprises two polishingstations 243 a, 243 b, one load cup 244, and a carousel 242 configuredto align three polishing heads 245 a, 245 b, 245 c with the polishingstations 243 a, 243 b, and the load cup 244. The polishing modules 231,241 are disposed symmetrically with the load cups 234, 244 next to oneanother.

The polishing robot 203 may be positioned in equal distance to thepolishing cups 234, 244. During processing, the polishing robot 203transfers unpolished substrates from the substrate transferringmechanism 202 to the load cups 234, 244, and transfer polishedsubstrates from the load cups 234, 244 to the cleaning assembly 205. Thepolishing robot 203 may also transfer substrates between the load cups234, 244 if the polishing recipe requires substrates to be polished inboth the polishing modules 231, 241.

The polishing assembly 204 of the present invention may be used toperform a two step polishing in parallel, a four step polishing inseries, or a three step polishing by splitting a long polishing step intwo polishing stations. Parallel Two Step Polishing

An exemplary two step polishing may be performed parallel in thepolishing modules 231, 241. For example, in the polishing module 231,the polishing station 233 a is configured to perform step one while thepolishing station 233 b is configured to perform step two.

During processing, the polishing robot 203 drops off a first unpolishedsubstrate in the load cup 234 and the polishing head 235 c can pick upthe first substrate thereon.

The carousel 232 may then rotate to align the polishing head 235 c withthe polishing station 233 a where the first polishing step is performedon the first substrate. At the same time, the polishing head 235 a isaligned with the load cup 234, where a second substrate may be loaded onthe polishing head 235 a.

Upon completing the first polishing step, the carousel 232 rotates againto align the polishing head 235 c with the polishing station 233 b wherethe second polishing step is performed to the first substrate. At thesame time, the polishing head 235 a is aligned with the polishingstation 233 a wherein the first polishing step is performed to thesecond substrate. At the same time, the polishing head 235 b is alignedwith the load cup 234, wherein a third substrate may be loaded onto thepolishing head 235 b.

Upon completion of polishing steps in both polishing stations 233 a, 233b, the carousel 232 may rotate again to align the polishing head 235 cwith the load cup 234, wherein the first substrate is unloaded andsubsequently transferred to the cleaning assembly 205 by the polishingrobot 203. A fourth substrate may be transferred to the load cup 234 bythe polishing robot 203 from the substrate transferring mechanism 202.The fourth substrate is then loaded on the polishing head 235 c andwaiting for the completion of polishing to the second and thirdsubstrates in the polishing stations 233 a, 233 b. The process may berepeated.

Similarly, in the polishing module 241, the polishing station 243 a isconfigured to perform step one while the polishing station 243 b isconfigured to perform step two. And a similar polishing process may beperformed in parallel.

Four Step Polishing

An exemplary four step polishing may be performed in the polishingmodules 231, 241. For example, the polishing station 233 a is configuredto perform step one, the polishing station 233 b is configured toperform step two, the polishing station 243 a is configured to performstep three, and the polishing station 243 b is configured to performstep four.

During processing, the polishing robot 203 drops off a first unpolishedsubstrate in the load cup 234 and the polishing head 235 c can pick upthe first substrate thereon.

The carousel 232 may then rotate to align the polishing head 235 c withthe polishing station 233 a where the first polishing step is performedon the first substrate. At the same time, the polishing head 235 a isaligned with the load cup 234, where a second substrate may be loaded onthe polishing head 235 a.

Upon completing the first polishing step, the carousel 232 rotates againto align the polishing head 235 c with the polishing station 233 b wherethe second polishing step is performed to the first substrate. At thesame time, the polishing head 235 a is aligned with the polishingstation 233 a wherein the first polishing step is performed to thesecond substrate. At the same time, the polishing head 235 b is alignedwith the load cup 234, wherein a third substrate may be loaded onto thepolishing head 235 b.

Upon completion of polishing steps in both polishing stations 233 a, 233b, the carousel 232 may rotate again to align the polishing head 235 cwith the load cup 234, wherein the first substrate is unloaded andsubsequently transferred to the load cup 244, wherein the firstsubstrate is loaded on the polishing head 245 b. A fourth substrate maybe transferred to the load cup 232 by the polishing robot 203 from thesubstrate transferring mechanism 202. The fourth substrate is thenloaded on the polishing head 235 c and waiting for the completion ofpolishing to the second and third substrates in the polishing stations233 a, 233 b. The process is repeated.

After loading the first substrate in the polishing head 245 b, thecarousel 242 may then rotate to align the polishing head 245 b with thepolishing station 243 a where the third polishing step is performed onthe first substrate. At the same time, the polishing head 245 c isaligned with the load cup 244, where the second substrate is transferredfrom the load cup 234 and may be loaded on the polishing head 245 c.

Upon completing the third polishing step, the carousel 242 rotates againto align the polishing head 245 b with the polishing station 243 b wherethe fourth polishing step is performed to the first substrate. At thesame time, the polishing head 245 c is aligned with the polishingstation 243 a wherein the third polishing step is performed to thesecond substrate. At the same time, the polishing head 245 a is alignedwith the load cup 244, wherein the third substrate is transferred fromthe load cup 234 and may be loaded onto the polishing head 245 a.

Upon completion of polishing steps in both polishing stations 243 a, 243b, the carousel 242 may rotate again to align the polishing head 245 awith the load cup 244, wherein the first substrate is unloaded andsubsequently transferred to the cleaning assembly 205. The fourthsubstrate is then in queue in the load cup 244, wherein the fourthsubstrate is loaded on the polishing head 245 b. At the same time, thesecond and third substrates are being polished in the polishing stations243 a, 243 b. Upon completion of the polishing, the process is repeated.

Three Step Polishing

In one embodiment, a three step polishing may be performed using thepolishing assembly 204. In one embodiment, the longest polishing step ofthe process may be split and performed in two consecutive steps. Inanother embodiment, the longest polishing step may be split to twoparallel steps. Thus, the three step polishing becomes a four steppolishing. An exemplary process may be similar to the four steppolishing described above.

The cleaning assembly 205 is configured to remove dislodged particlesand the abrasive polishing material from polished substrates, and thenrinse and dry the polished substrates. There are a number of differentcleaning methods and mechanisms that may be used individually or incombination in a given cleaning process. For example, a cleaningsequence may include Megasonic vibration, brush-scrubbing and/or bevelcleaning, in addition to further rinsing and drying procedures. The typeand number of procedures employed may vary depending on thesemiconductor device processing application.

In one embodiment, the cleaning assembly 205 may be a modular,configurable system in which distinct cleaning and drying modules can bearranged in different combinations selectable by a user of the system. Adetailed description of a modular cleaning system may be found in U.S.patent application Ser. No. 11/963,458, filed Dec. 21, 2007, entitled“Systems and Methods for Modular and Configurable Substrate Cleaning”(Attorney Docket No. 10860), which is incorporated herein by reference.

In one embodiment, the cleaning assembly 205 may comprises a substratereceiving dock 251, wherein polished substrates may be dropped off bythe polishing robot 203. The receiving dock 251 may have a substratehandler configured to orient the substrates in desired orientations forsubsequent cleaning process. For example, the substrates are generallyhorizontally oriented with device side facing down during polishing,while the substrates may be required to be vertical, or horizontal butwith device side facing up. An exemplary substrate receiving dock andsubstrate handler may be found in U.S. patent application Ser. No.12/026,000, filed Feb. 5, 2008, entitled “Edge Contact Gripper”(Attorney Docket No. 12113), which is incorporated herein by reference.

The cleaning assembly 205 further comprises a wet cleaning module 252wherein polished substrates may be cleaned to remove particles from thesubstrates. The wet cleaning module 252 may use various cleaningmethods, such as Megasonic vibration, brush-scrubbing, bevel cleaning,and rinsing. Cleaning and rinsing solutions are generally used in thewet cleaning module 252, and substrates stays wet. The wet cleaningmodule 252 may comprise vertical cleaners, horizontal cleaners, or thecombination of vertical and horizontal cleaners. Detailed description ofwet cleaner modules may be found in U.S. patent application Ser. No.11/963,458, filed Dec. 21, 2007, entitled “Systems and Methods forModular and Configurable Substrate Cleaning” (Attorney Docket No.10860), and U.S. patent application Ser. No. 11/961,587, filed Dec. 20,2007, entitled “Horizontal Megasonic Module for Cleaning Substrates”(Attorney Docket No. 10858), which are incorporated herein by reference.

The cleaning assembly 205 further comprises a dryer 254 configured toremove any vapor of cleaning and rinsing solution from cleanedsubstrates. Detailed description of an exemplary dryer may be found inU.S. patent application Ser. No. 11/967,533, filed Dec. 31, 2007,entitled “Multiple Substrate Vapor Drying System and Methods” (AttorneyDocket No. 10857), which is incorporated herein by reference.

The cleaning assembly 205 may further comprise a cleaning robot 253configured to transfer substrates within the cleaning assembly 205. Forexample, the cleaning robot 253 may transfer substrates within the wetcleaning module 252 or from the wet cleaning module 252 to the dryer254.

The dryer 254 may be positioned adjacent the inlet port 215 of thefactory interface 201 so that the internal robot 211 of the factoryinterface 211 may retrieve polished, cleaned and dried substrates at anoutlet of the dryer 254.

FIG. 4 is a schematic plan view of a polishing system 200 a inaccordance with another embodiment of the present invention. Thepolishing system 200 a is similar to the polishing system 200 of FIG. 3except that the polishing system 200 a comprises a polishing assembly207 which is different from the polishing assembly 204 of the polishingsystem 200. The polishing assembly 207 comprises two different polishingmodules 241 and 271, and is configured to optimize a three steppolishing with a long step.

The polishing assembly 207 is modular and configured to performdifferent polishing recipes. In one embodiment, the polishing module 241may be similar to the polishing module 100 of FIG. 1.

The polishing module 271 comprises two polishing stations 273 a, 273 b,one load cup 276, and two polishing head assembly 272 a, 272 b. Thepolishing head assembly 272 a comprises a pivoting arm 274 a and apolishing head 275 a mounted on the pivoting arm 274 a. The pivoting arm274 a is configured to align the polishing head 275 a with the load cup276 during loading/unloading, and to align the polishing head 275 a withthe polishing station 273 a during polishing. The polishing headassembly 272 b comprises a pivoting arm 274 b and a polishing head 275 bmounted on the pivoting arm 274 b. The pivoting arm 274 b is configuredto align the polishing head 275 b with the load cup 276 duringloading/unloading, and to align the polishing head 275 b with thepolishing station 273 b during polishing. The configuration of thepolishing module 271 increases flexibility of the polishing assembly 207and also reduces cross contamination by limiting the polishing heads 275a, 275 b to one polishing station.

The polishing modules 231, 271 are disposed symmetrically with the loadcups 276, 244 next to one another.

The polishing assembly 207 of the present invention may be used toperform various polishing processes. Particularly, the polishingassembly 207 may be used to perform a three step polishing process witha long step one or a long step two.

Three Step Polishing with a Long Step One

An exemplary three step polishing with a long step one may be performedin the polishing modules 271, 241. For example, the polishing station273 a and 273 b are both configured to perform step one, the polishingstation 243 a is configured to perform step two, and the polishingstation 243 b is configured to perform step three. The longest step,step one in this example, is performed in two polishing stations 273 a,274 a, while the shorter steps are performed in series in the polishingmodule 241 having a three headed carousel.

During processing, the polishing robot 203 drops off a first unpolishedsubstrate in the load cup 276 and the polishing head 275 a can pick upthe first substrate thereon.

The pivoting arm 274 a may then pivot to align the polishing head 275 awith the polishing station 273 a where the first polishing step isperformed on the first substrate.

Upon the polishing head 275 a vacant the load cup 276, a secondsubstrate may be dropped off of the polishing robot 203. The polishinghead 275 b may be aligned with the load cup 276, where the secondsubstrate may be loaded on the polishing head 275 b. The pivoting arm274 b may then pivot to align the polishing head 275 b with thepolishing station 273 b where the first polishing step is performed onthe second substrate.

Upon completing the first polishing step to the first substrate, whilethe second substrate is still being polished, the pivoting arm 274 apivots again to align the polishing head 275 a with the load cup 276wherein the first substrate is unloaded and subsequently transferred tothe load cup 244 of the polishing module 241. A third substrate may bedelivered to the load cup 276 and loaded on the polishing head 275 a.The polishing head 275 a is then pivoted to the polishing station 273 ato perform the first polishing step to the third substrate.

The process described above may be repeated for the subsequentsubstrates.

After transferred to the load cup 244, the first substrate is loadedonto the polishing head 245 b. After loading the first substrate in thepolishing head 245 b, the carousel 242 may then rotate to align thepolishing head 245 b with the polishing station 243 a where the secondpolishing step is performed on the first substrate. At the same time,the polishing head 245 c is aligned with the load cup 244, where thesecond substrate is transferred from the load cup 276 and may be loadedon the polishing head 245 c.

Upon completing the second polishing step to the first substrate andloading the second substrate on the polishing head 245 c, the carousel242 rotates again to align the polishing head 245 b with the polishingstation 243 b where the third polishing step is performed to the firstsubstrate. At the same time, the polishing head 245 c is aligned withthe polishing station 243 a wherein the second polishing step isperformed to the second substrate. At the same time, the polishing head245 a is aligned with the load cup 244, wherein the third substrate istransferred from the load cup 276 and may be loaded onto the polishinghead 245 a.

Upon completion of polishing steps in both polishing stations 243 a, 243b, the carousel 242 may rotate again to align the polishing head 245 awith the load cup 244, wherein the first substrate is unloaded andsubsequently transferred to the cleaning assembly 205. The fourthsubstrate is then in queue in the load cup 244, wherein the fourthsubstrate is loaded on the polishing head 245 b. At the same time, thesecond and third substrates are being polished in the polishing stations243 a, 243 b. Upon completion of the polishing, the process may berepeated for subsequent substrates.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

1. A polishing module configured to use in a polishing system,comprising: a base member; two polishing stations disposed on the basemember, wherein each of the two polishing stations is configured topolish substrates; a carousel supported by the base member, wherein thecarousel comprises three substrate heads each configured to transfer asubstrate and polish the substrate against the two polishing stations,and the carousel is configured to simultaneously rotate the threesubstrate heads about a carousel axis; and a load cup disposed on thebase member, wherein the load cup is configured to load substrates tothe three substrates heads and to unload substrates from the threepolishing heads, and the two polishing stations and the load cup arepositioned to allow simultaneous alignment of each of the threesubstrate heads with one of the two polishing stations and the load cup.2. The polishing module of claim 1, wherein the three substrate headsare mounted on a carousel base at equal angular intervals about thecarousel axis.
 3. The polishing module of claim 1, wherein each of thethree substrate heads is independently operable.
 4. The polishing moduleof claim 1, wherein each of the three substrate heads has a radialmovement relative to the carousel axis.
 5. The polishing module of claim4, wherein the radial movement provides a sweeping motion duringpolishing.
 6. The polishing module of claim 1, wherein each of the twopolishing stations comprises: a platen rotatable about a central axis; apolishing pad disposed on the platen, wherein the polishing pad has apolishing surface configured to polishing the substrate; a polishingsolution dispenser configured to deliver polishing solution on to thepolishing surface; and a conditioner assembly configured to clean andmaintain the polishing pad.
 7. A polishing system, comprising: a factoryinterface configured to receive unpolished substrates from substratetransferring cassettes and transfer polished substrates to the substratetransferring cassettes; a substrate transferring platform configured toreceive substrates from the factory interface; a polishing assemblyconfigured to polishing substrates in one or more polishing steps,wherein the polishing assembly comprises a first polishing modulecomprises: a first base member; first and second polishing stationsdisposed on the first base member; a first carousel supported by thefirst base member, wherein the first carousel comprises three substrateheads each configured to transfer a substrate and polish the substrateagainst the first and second polishing stations, and the first carouselis configured to simultaneously rotate the three substrate heads about afirst carousel axis; and a first load cup disposed on the first basemember, wherein the first polishing station, the second polishingstation and the first load cup are positioned to allow simultaneousalignment of each of the three substrate heads of the first carouselwith one of the first polishing station, the second polishing stationand the first load cup; a polishing robot configured to transfersubstrates from the substrate transferring platform to the polishingassembly; and a cleaning assembly to clean polished the substrates. 8.The polishing system of claim 7, wherein the polishing assembly furthercomprises a second polishing module disposed against the first polishingmodule.
 9. The polishing system of claim 8, wherein the second polishingmodule comprises: a second base member; third and fourth polishingstations disposed on the second base member; a second carousel supportedby the second base member, wherein the second carousel comprises threesubstrate heads each configured to transfer a substrate and polish thesubstrate against the third and fourth polishing stations, and thesecond carousel is configured to simultaneously rotate the threesubstrate heads about a second carousel axis; and a second load cupdisposed on the second base member, wherein the third polishing station,the fourth polishing station and the second load cup are positioned toallow simultaneous alignment of each of the three substrate heads of thesecond carousel with one of the third polishing station, the fourthpolishing station and the second load cup, wherein the polishing robotis configured to transfer substrates between the first and second loadcups.
 10. The polishing system of claim 8, wherein the second polishingmodule comprise: a second base member; third and fourth polishingstations disposed on the second base member; a second load cup disposedon the second base member; a first polishing arm comprising a substratehead, and is configured to pivot the substrate head to align thesubstrate head with the third polishing station and the second load cup;a second polishing arm comprising a substrate head, and is configured topivot the substrate head to align the substrate head with the fourthpolishing station and the second load cup, wherein the polishing robotis configured to transfer substrates between the first and second loadcups
 11. The polishing system of claim 7, wherein the polishing robot isconfigured to transfer polished substrates to the cleaning assembly. 12.The polishing system of claim 11, wherein the cleaning assemblycomprises: a wet cleaning device; a dry cleaning device; and a cleaningrobot configured to transfer substrates from the wet cleaning device tothe dry cleaning device.
 13. The polishing system of claim 12, whereinthe factory interface comprises an internal robot, and the internalrobot is configured to transfer substrates from the dry cleaning deviceto the factory interface after a dry cleaning process.
 14. The polishingsystem of claim 7, wherein the substrate transferring platform comprisesa substrate transferring belt configured to receive substrates from aninternal robot of the factory interface, and the polishing robot isconfigured to pick substrates from the substrate transferring belt tothe first load cup.
 15. The polishing system of claim 7, wherein thethree substrate heads of the first polishing module are mounted on thefirst carousel base at equal angular intervals about the first carouselaxis.
 16. A method for polishing a substrate, comprising: transferring afirst substrate using a substrate transferring belt towards a polishingassembly; transferring the first substrate from the substratetransferring belt to a first load cup of the polishing assembly; loadingthe first substrate from the first load cup to a first substrate headmounted on a first carousel having three polishing heads; aligning thefirst substrate head with a first polishing station of the polishingassembly; polishing the first substrate in the first polishing station;aligning the first substrate head with the first load cup; and unloadingthe first substrate from the first substrate head to the first load cup.17. The method of claim 15, wherein aligning the first substrate headcomprises: rotating the first carousel; and moving the first substratehead radially.
 18. The method of claim 15, further comprising: uponfinishing polishing the first substrate in the first polishing station,rotating the carousel; moving the first substrate head radially to alignwith a second polishing station; and polishing the first substrate inthe second polishing station.
 19. The method of claim 15, furthercomprising: while aligning the first substrate head with the firstpolishing station of the polishing assembly, simultaneously loading asecond substrate on a second substrate head of the first carousel byaligning the second substrate head with the first load cup; aligning thefirst substrate head with a second polishing station of the polishingassembly and simultaneously aligning the second substrate head with thefirst polishing station; and polishing the first substrate in the secondpolishing station and simultaneously polishing the second substrate inthe second polishing station;
 20. The method of claim 15, furthercomprising: after unloading the first substrate to the first load cup,transferring the first substrate from the first load cup to a secondload cup of the polishing assembly; loading the first substrate to athird substrate head of a second carousel having three polishing heads;aligning the third substrate head with a third polishing station byrotating the second carousel; and polishing the first substrate at thethird polishing station.